<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="https://cdn.jsdelivr.net/npm/vue@2.6.14"></script>
</head>
<body>
  <div id='root'></div>
  <script>
    // log 插件
    const logger = {
      install(Vue, options) {
        // 参数的处理
        // ...
        Object.defineProperty(Vue.prototype, '$log', {
          value: () => console.log('打印日志啦~'),
          configurable: false,
          enumerable: false,
          writable: false
        })
      }
    }

    Vue.use(logger)

    new Vue({
      el: document.querySelector('#root'),
      template: `<h1>hello world!</h1>`,
      created() {
        this.$log();
      }
    })
  </script>
</body>
</html>